JP5084844B2 - System and method for reducing exhaust noise of a jet engine - Google Patents

Description

  The present invention generally includes noise from jet engines (e.g., broadband noise), including through a nozzle having a chevron structure or other protrusion that is reinforced by the proximity of jets and / or other mixing enhancement devices. Is related to a system and method.

  Aircraft manufacturers are constantly under pressure to reduce the noise generated by aircraft in order to meet increasingly stringent noise certification standards. Aircraft engines are the main source of overall aircraft noise. Therefore, noise reduction efforts by manufacturers have been specifically targeted at aircraft engines. Aircraft engines are becoming much quieter as a result of using advanced high bypass ratio engines. With these engines, a significant proportion of the total propulsion is not obtained directly from the jet exhaust, but from bypass air propelled around the engine core by a forward-mounted engine-driven fan. Although this approach significantly reduces aircraft noise compared to pure turbojet and low bypass ratio engines, the engine and aircraft federal regulations still require further engine noise reduction. .

  Several techniques have been used to reduce engine exhaust noise. One way to reduce engine noise is to adjust the amount of high-speed gas exiting the engine and the ambient free-flowing air. A specific approach involves forming a “chevron” at the nozzle outlet. The chevron is generally serrated at the nozzle edge, usually triangular, and includes some curvature in the longitudinal direction, so it is slightly exposed to the adjacent flow. The chevron can project inward or outward by approximately the thickness of the upstream boundary layer on the inner or outer surface, respectively. The chevron can be located at the rear edge of the nozzle center flow duct (through which the engine center flow is directed) and / or at the rear edge of the fan flow duct. The flow duct is annularly arranged around the central flow duct, and the bypass air of the fan flows therethrough. Chevron typically reduces low frequency noise by adjusting the rate at which the nozzle stream mixes with the free stream of ambient air on the nozzle diameter length scale. Another approach in which similar noise reduction is feasible is to generate a high pressure fluid jet (eg, microjet) at or near the nozzle outlet. The approach described above provides significant noise reduction compared to nozzles that do not include chevron or fluid jets, but further noise reduction is desirable to meet environmental noise standards and reduce in-flight noise.

  The following summary is provided to assist the reader and is not intended to limit the invention as claimed. Particular aspects of the present disclosure relate to jet engine nozzles that include both trailing edge protrusions (eg, chevrons) and proximately located injection ports, and related systems and methods. One method of controlling aircraft engine nozzle flow is to generate a first flow of gas by a jet engine and deliver the first flow through a nozzle having a trailing edge perimeter that includes a plurality of rearwardly extending protrusions (chevrons). Including a step. The method can further include injecting a second stream of pressurized gas into the first stream at least proximate to the protrusion. In a specific embodiment of this method, the protrusion is generally triangular and the triangular tip region is located at the rear of the base region. The second flow is jetted at a position aligned with the tip region and the axial direction in the flow direction. In yet another specific aspect, the second flow can be changed or stopped based at least in part on engine operating parameters, aircraft flight conditions, or both. For example, the second flow can be reduced or stopped when the aircraft is in a cruise state. In another aspect, the second flow can be varied (eg, pulsed).

  Another aspect relates to a method of making an aircraft nozzle system. The above-mentioned method is applied to a nozzle having an outlet having a circumferentially changing outlet outer peripheral shape, and the generation level of the turbulent kinetic energy of the jet flow at the nozzle outlet is higher than the average of the generation level of the surrounding turbulent kinetic energy. Identifying a target position around the nozzle outlet that is expected to be higher. The method can further include disposing a mixing intensifier (eg, a vortex generator, an elongated extension, and / or a fluid jet). In a particular embodiment, the nozzle includes a protrusion on the outer periphery of the outlet, the protrusion having a generally triangular shape having a tip located at the rear of the base. The positioning of the mixing strengthening device is such that the individual injection ports are aligned in the flow direction along the axis of the tip of the corresponding projection, the injection port is located at the rear of the corresponding tip, and is acute with respect to the corresponding tip Positioning inwardly at an angle.

  According to another aspect, a method includes generating a flow of gas by a jet engine and delivering the flow through a nozzle having a trailing edge perimeter that includes a plurality of protrusions extending in a rearward direction. The method further includes the steps of increasing the vorticity of the flow, reducing the shear stress, or increasing the vorticity to reduce the shear stress at a location proximate to the protrusion. In yet another aspect, the vorticity of the flow in the tip region of the protrusion is increased and / or the shear stress is reduced via the mixing intensifier. The mixing intensifier can include a vortex generator, an elongated extension, and / or a fluid ejection port.

  Yet another aspect relates to an aircraft system including an exhaust nozzle of a jet engine having an outlet having a circumferential length including a plurality of protrusions extending in a rearward direction. The system may further include a plurality of injection paths having openings located at least proximate to the protrusions, the injection paths being connected to a source of pressurized gas.

  In a more specific aspect, the system can also include one or more valves connected to the one or more injection paths for controlling flow through the one or more injection paths. The system may further comprise a controller operably connected to the one or more valves, the controller programmed to receive input values corresponding to engine operating conditions, flight conditions, or both. Yes. The controller is also programmed to induce the valve based at least in part on the input value.

  Yet another aspect relates to an aircraft system comprising a jet engine nozzle having an outlet having a perimeter that includes a plurality of protrusions extending in a rearward direction. The system further includes a mixing strengthening device disposed on the protrusion, which increases the vorticity, weakens the shear stress, or increases the vorticity at a position close to the protrusion. Is arranged to bring about both effects. For example, the mixing strengthening device can include an injection path that has an opening located at least in proximity to the protrusion and is connected to a source of pressurized gas. In another configuration, the shape of the protrusion is generally triangular with a tip located at the rear of the base, and the mixing and strengthening device includes an elongated extension extending in the rear direction from the tip of the protrusion.

FIG. 1 is a diagram illustrating an aircraft having a nozzle constructed in accordance with an embodiment of the present invention. FIG. 2 is a view showing a nozzle having a protrusion and an injection path configured according to an embodiment of the present invention. FIG. 3 is an enlarged plan view showing a part of a nozzle having a protrusion and an ejection path according to an embodiment of the present invention. FIG. 4 is a partially schematic cross-sectional side view showing a nozzle protrusion and an associated injection path together with a control device configured according to an embodiment of the present invention. FIG. 5 is a graph showing test data comparing nozzles with and without a protrusion and a jet according to an embodiment of the present invention. FIG. 6 is a partial schematic diagram illustrating nozzles disposed proximate to an aircraft fuselage according to another embodiment of the present invention. 7A and 7B are diagrams illustrating a nozzle protrusion having enhanced noise attenuation performance according to another embodiment of the present invention. 8A-B are diagrams illustrating nozzle protrusions having enhanced noise attenuation performance according to another embodiment of the present invention. 9A-B are diagrams illustrating nozzle protrusions having enhanced noise attenuation performance according to another embodiment of the present invention. 10A and 10B are diagrams illustrating nozzle protrusions having enhanced noise attenuation performance according to another embodiment of the present invention.

  Aspects of the present disclosure relate to jet engine nozzles having chevrons or other protrusions, mixing intensifiers, and associated systems and methods. Detailed information for a particular embodiment is described below with reference to FIGS. Some details of the structures or processes that are known and often associated with the systems and processes are not described in the following description for the sake of brevity. Furthermore, while the following disclosure describes several embodiments of different aspects of the invention, some other embodiments of the invention may have different configurations or different elements than those described in this section. May have. Accordingly, the present invention may be implemented with other elements that use additional elements and / or that do not use the various elements described below with reference to FIGS. 1-10B.

  FIG. 1 is a diagram illustrating a private jet transport aircraft 100 having a wing 102, a fuselage 101, and a propulsion system 103. The illustrated propulsion system 103 includes two engines 106 disposed on the wings 102. Each engine 106 is stored in a nacelle 104 including an inlet 105 and a nozzle 120. Nozzle 120 includes both a rearward extending protrusion and a jet or other mixing enhancement arrangement that is described in more detail below and reduces noise generated from engine 106. The noise reduction achieved by these mechanisms can be applied to the engine arranged in the configuration shown in FIG. 1, or provided by other configurations including those described below with reference to FIG. Can be applied to the engine.

  2 is an enlarged front view of the nozzle 120 shown in FIG. 1 constructed in accordance with an embodiment of the present invention. The nozzle 120 can include a core flow path 122 that carries engine exhaust products and a fan flow path 121 that is annularly disposed around the core flow path 122 that carries the bypass air flow of the fan. The core channel 122 ends at the core outlet 124, and the fan channel 121 ends at the fan outlet 123. Either or both of the outlets 123, 124 may comprise a protrusion 125 having a “chevron” shape or another shape arranged to enhance mixing of the gas streams that merge at the corresponding outlet. For illustration purposes, the nozzle 120 has been shown as a nozzle having both a fan flow projection 125a and a core flow projection 125b, but in certain installation configurations, either one of the projections 125a, 125b can be eliminated. it can. In any of these embodiments, some or all of the protrusions 125 can include a corresponding mixing intensifier 150. In a specific arrangement, the mixing and strengthening device 150 includes an ejection path 126 (portion indicated by a dotted line in FIG. 2) having a flow path port 127. The ejection path 126 carries a high-pressure fluid (for example, a gas such as air or a liquid), and is generally oriented in the rear direction close to the protrusion 125. As will be described in more detail later, the combination of the high pressure flow introduced from the protrusion 125 and the injection path 126 (or other mixing and strengthening device) will reduce the amount of noise reduction that can be achieved by either the protrusion or the injection alone. The engine noise reduction is expected to be significant. A mixing intensifier including a jet is described further below with reference to FIGS. 3-8B, and other mixing intensifiers are described below with reference to FIGS. 9A-10B.

  FIG. 3 is an enlarged plan view of a portion of the nozzle 120 showing an exemplary protrusion 125 constructed in accordance with an embodiment of the present invention. In this particular embodiment, the protrusion 125 has a generally chevron or triangular shape and its tip region 128 is located at the rear of the base region 129. The tip region 128 of each protrusion 125 is terminated at the rearmost tip 130. In one particular aspect of this embodiment, the jet passage 126 and the associated flow passage port 127 are aligned with the tip region 128 (in the direction of flow) along the axis. This arrangement of the flow path port 127 is considered to improve the noise reduction capability of the nozzle as compared to installing the flow path port 127 at other positions. Specifically, it is considered that the turbulent kinetic energy generated by the nozzle flow adjacent to the protruding portion 125 is higher in the vicinity of the tip portion 130 than in the vicinity of the base region 129. Furthermore, the generation level of turbulent kinetic energy is believed to be reduced by the introduction of high pressure microjet jets. Accordingly, the channel port 127 can be intentionally placed at or near the tip 130 to offset the expected level of turbulent kinetic energy generation expected at this location. Furthermore, with this arrangement, the noise level is expected to be reduced below the level achievable with only the protrusion 125.

  Further, as shown in FIG. 3, the individual flow path ports 127 can be arranged at the rear portions of the corresponding tip portions 130. In certain embodiments, the channel port 127 is located just behind the tip 130. For example, each flow path port 127 can be arranged at a length about 20% of the axial length of the protrusion 125 downstream of the corresponding tip portion 130. While at least some embodiments are expected to provide better noise reduction at the downstream location, in other embodiments, the channel port 127 is located at the tip 130 or just upstream of the tip 130. Can be arranged. Therefore, in yet another embodiment, the flow path port 127 has a corresponding tip portion that is a distance that maximizes the diameter of about one nozzle (for example, the diameter of the nozzle 120 at the outer peripheral position where the protrusion 125 extends). 130 downstream. For purposes of illustration, a single channel port 127 is shown for each protrusion 125. In another embodiment, each protrusion includes a plurality of adjacent channel openings 127 near the tip 130. With this arrangement, it is possible to reduce the size of each flow path port 127 and the associated injection path 126 without reducing the mass flow rate to be injected. The channel port 127 can be oriented such that the azimuth angle Z is zero (as shown in FIG. 3), or in other embodiments, a non-zero azimuth angle. When the protrusion 125 includes a single channel port 127 and / or when the protrusion 125 includes a plurality of channel ports 127, the azimuth angle Z may be non-zero. In the latter case, the channel openings 127 of certain protrusions 125 can be oriented in directions of each other or in directions away from each other.

  In addition to retracting the nozzle 126, the protrusion 125 may be movable relative to the remainder of the nozzle 120 in at least some embodiments. For example, the protrusion 125 can rotate relative to the rest of the nozzle 120 along the hinge line 131 to change the degree to which each protrusion 125 is immersed (tilted relative to) the upstream nozzle flow. In another arrangement, the protrusion 125 may be made of a resilient and flexible material that, during operation, forms a continuously curved immersion surface instead of a surface having a discontinuity in the hinge line 131. To do. By adjusting the flow through the injection path 126, optionally in combination with the adjustment of the orientation of the protrusion 125, the noise reduction and overall efficiency of the nozzle 120, as described below with reference to FIG. It is adjustable.

  FIG. 4 is a partial cross-sectional side view of a part of the nozzle 120, one of the protrusions 125, and a partial jet path 126 associated therewith. The injection path 126 is connected to a pressurized gas supply source 140. The supply source 140 can supply pressurized air or another gas (for example, exhaust gas) to the injection path 126. In certain embodiments, the source 140 may comprise an engine compressor that supplies compressed air to the injection passage 126 via a bleed air port. In another embodiment, the high pressure air can be supplied by another source, such as an aircraft auxiliary power unit (APU).

  As described above, the flow path port 127 can be arranged side by side with the tip portion 130 of the protrusion 125 in the flow direction along the axis. As shown in FIG. 4, the flow axis of the ejection path 126 in the flow path port 127 can be inclined by an angle A with respect to the adjacent flow direction of the gas passing along the inner surface 132 of the nozzle 120 (indicated by an arrow G). ). The inclination angle A may be an acute angle having a value selected from 0 ° to ± 90 °. In one particular embodiment, the tilt angle A is about 60 ° with respect to the internal gas flow direction G. The particular tilt angle A selected for the channel port 127 may be a different value in other embodiments, among other factors, the nozzle pressure ratio, the particular nozzle shape characteristics, and the protrusion 125. It is possible to select for specific installation conditions based on factors that can include various shapes. For example, if the protrusion 125 is immersed inward (as shown in FIG. 4), the angle A can have a positive value. In installation conditions where there are multiple flows (for example, having a bypass flow located annularly outward from the center flow), the protrusion 125 is placed between the two flows and the bypass flow is directed outward. Can be immersed in In the above case, the angle A can have a negative value. In certain embodiments, the flow passage port 127 is circular. In other embodiments, the shape and / or size of the channel port 127 may be different, for example, depending on engine and nozzle size and / or installation details.

  The aspect of the protrusion 125 and / or the injection path 126 can be selectively changed and / or otherwise controlled during operation. For example, when the protrusion 125 is movable with respect to the remaining portion of the nozzle 120, the nozzle 120 includes one or more actuators 134 connected to the protrusion 125, and the degree of immersion of each protrusion 125 is changed. The protrusion 125 can be rotated (as indicated by arrow I). The protrusions 125 can be controlled to move individually or all together relative to each other.

  Flexible to at least some portions of the injection path 126 to accommodate relative movement of the protrusion 125 and also to accommodate other movable functions of the nozzle 120 (including but not limited to reverse propulsion functions). Flexible tubing or other adjustable, adaptable and / or resilient structures may be provided. The injection path 126 may be connected to one or more valves 135 to control the flow through each injection path 126 and the associated flow port 127.

  A controller 136 may be operably connected to the valve 135 and actuator 134 to manage the operation of these elements during flight. Controller 136 may provide engine input value 137 (eg, engine thrust level), flight status input value 138 (eg, takeoff, landing, cruise, or other current and / or future flight status indications), and / or others. Input value 139 (eg, pilot input value) can be received. Based on the input values 137-139, the controller 136 can manage the movement of the protrusion 125 and / or the flow rate through the ejection path 126. For example, in situations where noise reduction is of relatively high importance, the controller 136 can manage the maximum (or relatively high) flow rate through the injection path 126 and, optionally, the protrusion 125 can be configured to maximize The immersion angle can be moved to the expected reduction. The above situation may occur during takeoff when the engine is set to or approaches the maximum thrust level. In other situations, including but not limited to cruise situations, the need to run the engine efficiently may exceed the need to reduce engine noise above a threshold level. Therefore, the flow of compressed air through the injection path 126 can be reduced or stopped by the controller 136, and the immersion angle I of the protrusion 125 can be adjusted to zero or close to zero. In certain embodiments, the controller 136 may comprise a feedback loop for controlling exhaust noise. For example, other input values 139 may include input values from microphones, pressure sensors, or other sensors that directly or indirectly detect engine exhaust noise levels. The controller 136 then adjusts the operational parameters of the protrusion 125 and / or the injection path 126 to obtain a desired (eg, optimal) level of noise reduction. In all the situations described above, the flow can be changed in a manner such that, for example, in pulses, or otherwise the variation is managed by time. The parameters described above can be adjusted automatically based on received input values and / or can be overridden, adjusted, or otherwise manipulated by the pilot. The controller 136 may thus comprise a processor, memory, a computer having input / output capabilities, and a computer readable medium having instructions executable by the computer. The functionality of the computer can be integrated into an existing aircraft computer, or the computer can comprise a stand-alone unit that communicates with other aircraft systems.

  In order to reduce the impact on engine efficiency associated with removing flow from the engine, it is usually desirable to inject the minimum flow required to obtain the desired noise reduction. In general, it is expected that the injection flow rate may be less than or equal to 5% of the total engine mass flow rate. For example, in certain embodiments, it is anticipated that in takeoff conditions, the injection flow rate may be about 1% or less (eg, 0.5%) of the overall engine mass flow rate. As described above, the injection flow rate can be reduced or eliminated at other engine settings and / or flight conditions.

  One feature of at least some of the above-described embodiments is that the flow of fluid (eg, gas or liquid) through the injection path 126 is a relative need for noise reduction and a relative need for efficient engine operation. It can be adjusted to change with sex. This configuration can be complemented by a movable protrusion 125, but may be easier to implement than a movable protrusion and can therefore be used in place of the movable protrusion 125. An advantage of this configuration is that it may be possible for an operator to control engine noise reduction and efficiency with a relatively simple valve arrangement (eg, valve 135, etc.).

  Another feature of at least some of the above-described embodiments is that the flow delivered by the jet path 126 provides a significant reduction in noise compared to the noise reduction achievable when using only the protrusion 125. Is expected to be. Therefore, it is possible to achieve an overall low noise level using the jet flow in combination with the protrusion 125. Noise reduction can be achieved over broadband noise, shock cell noise, noise audible on the ground (eg, particularly environmental noise during take-off), and / or noise audible in an aircraft (eg, particularly in cabin cabin during cruising). it can. Alternatively, the jet flow can be used to reduce or change the number of shapes of the protrusions 125 (eg, reduce the degree of immersion), so that only a larger number or different shapes of protrusions are performed. Equivalent noise level reduction is obtained. As a result, in some cases, the jet flow can reduce the overall weight of the aircraft by reducing the number of protrusions 125 and / or improve the performance of the aircraft.

  Yet another feature of at least some of the above-described embodiments is that the jet can be supplied to a position that complements the associated limitations when implemented with only the protrusions. For example, the test data shows that the protrusion alone provides high shear and / or low (or zero) axial vorticity in the tip region. By flowing the jet stream in the tip region, it is expected that shear stress will be reduced and / or the axial vorticity will be increased to improve overall noise reduction.

  FIG. 5 is a graph showing noise level measurements of three different nozzles as a function of angular position relative to the nozzle at a nozzle diameter of 100 radius. Thus, 90 ° on the X axis corresponds to a position that is longitudinally aligned with the nozzle and is laterally offset from the nozzle by a nozzle diameter of 100, and 180 ° is laterally aligned with the nozzle outlet, This corresponds to a position shifted in the axial direction (longitudinal direction) by the nozzle diameter 100 downstream. Line 140a shows data corresponding to a standard circular nozzle, line 140b shows data corresponding to a nozzle having a conventional chevron 18 with a relatively loose immersion angle, and nozzle 140c shows a homogeneous circular outlet periphery and an outer periphery. This coincides with a circular nozzle having a jet flow in the rear direction flowing out from the part. Line 140d corresponds to a nozzle having a chevron 18 shaped protrusion that combines with the flow injected in a manner generally similar to that described above with reference to FIGS. From these acoustic test data, it can be seen that the noise reduction benefits of nozzles having both protrusions and jets are significantly greater than noise reduction achieved by nozzles having only protrusions or only jets. For example, at many angular positions shown in FIG. 5, the noise reduction increases from about 1 dB to about 2 dB.

  FIG. 6 is a partial schematic rear front view showing an engine nacelle 604 and associated nozzle 620 mounted in close proximity to an aircraft fuselage 101 according to another embodiment of the present invention. In this embodiment, the nozzle 620 can include protrusions 625 (shown as fan flow protrusions 625a and core flow protrusions 625b), with some or all of the protrusions 625 being generally similar to the injection path described above. Road 627 is included. In this embodiment, the protrusion 625 and the ejection path 627 can have a size and a shape that can reduce noise not only for the observer on the ground but also for passengers inside the airframe 101. In other embodiments, the nacelle 604 may be located at a different location relative to the fuselage 101 and / or aircraft wing, and the protrusions and associated jet paths may be adjusted as necessary in a suitable manner. The

  In the system described above, the noise level of the nozzle can be reduced by adding axial vorticity generated from the protrusion and / or by reducing the shear stress near the tip of the protrusion. In other embodiments, the system can include different arrangements that achieve noise reduction by one or both of the mechanisms described above. A representative embodiment is described below with reference to FIGS. 7A-10B.

  FIG. 7A is a partially schematic plan view of a protrusion 725 provided with an injection path 726 according to another embodiment of the present invention. 7B is a partial schematic cross-sectional view of the protrusion 725 shown in FIG. 7A. Referring now to FIGS. 7A and 7B, the protrusion 725 includes an ejection path 726 having a channel port 727 that is offset outwardly from the inner surface 732 of the protrusion 725. The aerodynamic streamline (not shown in FIGS. 7A-7B) integrates the outer surface of the injection path 726 with the outer surface of the protrusion 725. In certain embodiments, the channel port 727 is offset from the inner surface 732 by an outward distance O, and the value selected for the distance O is associated with the size of the protrusion 725 and the channel port 727 as well as with it. Varies depending on the expected operating state of the nozzle. By shifting the flow path port 727 outwardly away from the shear layer emerging from the nozzle in the protrusion 725, the shear stress near the tip of the protrusion 725 is weakened and / or the axis of flow from the protrusion 725 in the rear direction. It is expected to be easier to increase the vorticity of the direction.

  8A-8B are a plan view and a cross-sectional view, respectively, of a protrusion 825 that injects a flow, according to another embodiment of the present invention. In this particular arrangement, the protrusion 825 includes an injection chamber 826 that communicates with the flow path port 827. The injection chamber 826 further includes a membrane 841 or other drivable device (eg, a piston or the like) that sends the flow inward and outward through the channel port 827. Thus, instead of providing a continuous flow of fluid, this arrangement creates a pulsed flow of fluid at the channel port 827. This arrangement is expected to have a beneficial effect on noise reduction by increasing the axial vorticity and / or reducing the shear stress near the tip of the protrusion 825. A further anticipated additional advantage of this arrangement is that it is simple to implement and / or is energy efficient.

  In the foregoing embodiment, the axial vorticity and / or shear stress level is beneficially affected by the combination of inlet flow and protrusions located at the nozzle outlet. In other embodiments, the beneficial effect imparted by the protrusion can be enhanced by a device that does not need to include a jet. A representative apparatus is described in further detail below with reference to FIGS. 9A-10B.

  FIGS. 9A and 9B are a plan view and a cross-sectional view, respectively, showing a protrusion 925 comprising a mixing and strengthening device 950 disposed toward a tip 930 according to one embodiment of the present invention. In this particular arrangement, the mixing intensifier 950 takes the form of an elongated pin that extends from the tip to the rear. The mixing strengthening device 950 is also oriented inward with respect to the inner surface 932 of the protrusion 925. It is expected that the mixing strengthening device increases the axial vorticity obtained only from the protrusion 925 and / or reduces the shear stress near the tip 930 of the protrusion 925.

  FIGS. 10A and 10B show a plan view and a cross-sectional view, respectively, of a protrusion 1025 comprising a mixing and strengthening device 1050 configured in accordance with another embodiment of the present invention. In this arrangement, the mixing and strengthening device 1050 also projects rearward from the tip 1030 and is inclined inward with respect to the inner surface 1032 of the protrusion 1025. The mixing strengthening device 1050 is integrated with or at least partially integrated with the outer contour of the protrusion 1025.

  From the above description, specific embodiments of the invention have been described herein for purposes of illustration, but various modifications may be made without departing from the invention. For example, the protrusion can have a shape other than a triangle. Each protrusion may comprise more than one channel and / or each channel may comprise more than one channel port. In certain embodiments, the channel port can be located flush with the tip of the corresponding protrusion, instead of extending downstream of the tip of the protrusion. Aspects of the invention described in certain embodiments can be combined with other embodiments or eliminated in other embodiments. For example, the mixing strengthening device and the protrusion can be disposed at one or both of the core outlet and the fan outlet. The mixing strengthening device and / or the protrusion may have a feature that changes in a circumferential direction around the nozzle. Further, while advantages relating to particular embodiments of the present invention have been described in these embodiments, other embodiments can also exhibit the advantages described above, and all embodiments are within the scope of the present invention. Therefore, it is not always necessary to exhibit the above advantages. Accordingly, the invention is not limited except as by the appended claims.

Claims (7)

Generating a first flow of gas by a jet engine;
Delivering a first stream through a nozzle having a trailing edge perimeter comprising a plurality of protrusions extending in a rearward direction;
Injecting a second flow of fluid toward a first flow at least proximate to the protrusion ;
Only including,
The projection is generally triangular, the tip region of the triangle is located at the rear of the base region, and the step of injecting the second flow includes a flow direction at a position where the second flow is aligned with the tip region along the axis. Injecting into
A method of controlling an aircraft engine nozzle flow , wherein the step of injecting a second flow comprises injecting a second flow at a location downstream of a tip of a tip region .   The method of claim 1, wherein injecting the second flow comprises directing the second flow at a non-zero azimuth angle with respect to the flow direction of the first flow.   The method of claim 1, further comprising changing, pulsing, or stopping the second stream injection based at least in part on engine operating parameters, aircraft flight conditions, or both. Method. The method of claim 1, further comprising moving the protrusion relative to the engine based at least in part on engine operating parameters, aircraft flight conditions, or both. The first flow generates the turbulent kinetic energy generation level of the jet flow that changes in the circumferential direction with respect to the average value in the peripheral length of the trailing edge, and the step of injecting the second flow is the turbulent kinetic energy generation level. The method of claim 1, comprising injecting a second flow at an outer circumferential position where is higher than an average value.   The method of claim 1, wherein injecting the second stream comprises injecting the second stream into a core stream of the engine.   The method of claim 1, wherein injecting the second stream comprises injecting the second stream into an engine bypass stream.

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